ios - ARKit - 如何创建旋转对象手势功能？

Question

我是ARKit的新手。我想创建一个旋转对象的函数。这是关于拖动和旋转对象的代码：

// Rotate object
@objc func rotateRecognized(sender: UIPanGestureRecognizer) {
    let sceneView = sender.view as! ARSCNView
    let swipeLocation = sender.location(in: sceneView)
    let hitTest = sceneView.hitTest(swipeLocation)
    if !hitTest.isEmpty {
        sender.minimumNumberOfTouches = 2
        let results = hitTest.first!
        let node = results.node
        let xPan = sender.velocity(in: sceneView).x/10000
        node.runAction(SCNAction.rotateBy(x: 0, y: xPan, z: 0, duration: 0.1))
    }
}

// Drag object
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    //1. Get The Current Touch Point
    guard let currentTouchPoint = touches.first?.location(in: self.sceneView),
        //2. Get The Next Feature Point Etc
        let hitTest = sceneView.hitTest(currentTouchPoint, types: .existingPlane).first else { return }

    //3. Convert To World Coordinates
    let worldTransform = hitTest.worldTransform

    //4. Set The New Position
    let newPosition = SCNVector3(worldTransform.columns.3.x, worldTransform.columns.3.y, worldTransform.columns.3.z)

    //5. Apply To The Node
    self.sceneView.scene.rootNode.enumerateChildNodes{ (node, _) in
       node.simdPosition = float3(newPosition.x, newPosition.y, newPosition.z)
    }

}

当我拖动一个对象时，它工作正常。但是当我用两根手指滑动旋转对象时，在删除touchesMoves方法之前，对象无法旋转。如何解决这个问题？谢谢。

Answer 1

我认为最好使用GestureRecognizers而不是touches和gestures的组合来解决这个问题。

让我们来看看，我们如何解决这个问题。

您已经具有拖动SCNNode的功能，这可以很容易地转换为UIPanGesture，并且您希望一个函数围绕它的YAx旋转SCNNode，我们可以很容易地使用UIRotationGestureRecognizer。

在我的例子中，我有一个名为currentNode的SCNNode，虽然你的当然会有所不同。

首先，我们将创建两个变量：

//Store The Rotation Of The CurrentNode
var currentAngleY: Float = 0.0

//Not Really Necessary But Can Use If You Like 
var isRotating = false

然后我们将在gestureRecognizers创建两个viewDidLoad：

 let panGesture = UIPanGestureRecognizer(target: self, action: #selector(moveNode(_:)))
 self.view.addGestureRecognizer(panGesture)

 let rotateGesture = UIRotationGestureRecognizer(target: self, action: #selector(rotateNode(_:)))
 self.view.addGestureRecognizer(rotateGesture)

完成此操作后，我们需要创建我们的功能。

第一个将处理拖动currentNode，例如：

/// Rotates An Object On It's YAxis
///
/// - Parameter gesture: UIPanGestureRecognizer
@objc func moveNode(_ gesture: UIPanGestureRecognizer) {

    if !isRotating{

    //1. Get The Current Touch Point
    let currentTouchPoint = gesture.location(in: self.augmentedRealityView)

    //2. Get The Next Feature Point Etc
    guard let hitTest = self.augmentedRealityView.hitTest(currentTouchPoint, types: .existingPlane).first else { return }

    //3. Convert To World Coordinates
    let worldTransform = hitTest.worldTransform

    //4. Set The New Position
    let newPosition = SCNVector3(worldTransform.columns.3.x, worldTransform.columns.3.y, worldTransform.columns.3.z)

    //5. Apply To The Node
    currentNode.simdPosition = float3(newPosition.x, newPosition.y, newPosition.z)

    }
}

第二个围绕它旋转它的YAxis：

/// Rotates An SCNNode Around It's YAxis
///
/// - Parameter gesture: UIRotationGestureRecognizer
@objc func rotateNode(_ gesture: UIRotationGestureRecognizer){

    //1. Get The Current Rotation From The Gesture
    let rotation = Float(gesture.rotation)

    //2. If The Gesture State Has Changed Set The Nodes EulerAngles.y
    if gesture.state == .changed{
        isRotating = true
        currentNode.eulerAngles.y = currentAngleY + rotation
    }

    //3. If The Gesture Has Ended Store The Last Angle Of The Cube
    if(gesture.state == .ended) {
        currentAngleY = currentNode.eulerAngles.y
        isRotating = false
    }
}

这是一个非常粗糙的例子，你需要看看不同的gestureStates等，但希望它能指出你正确的方向......